Many different types of rear suspension systems have been developed. These include solid-axle dependent suspensions and independent suspensions. The solid-axle dependent suspensions are typically used on load-carrying vehicles such as trucks. These suspensions are strong and sturdy but produce a somewhat harsh ride. Independent suspensions, commonly installed in passenger cars, offer a smoother ride and better handling, but they can be less rugged than the solid-axle suspension.
In the past, virtually all trucks and utility vehicles were used for load carrying and other rough work and so came equipped with solid-axle suspensions. However, now that trucks and sport utility vehicles are being sold as luxury and recreational vehicles, the comfortable ride provided by an independent suspension has become increasingly important.
Independent suspension designs commonly used for rear suspensions include semi-trailing arms, A-arms, short-long arms (SLAs), three links, four links, and five links. Unfortunately, installing one of these existing independent suspensions into a vehicle designed for a solid-axle suspension can result in mechanical conflicts in placement of components such as the fuel tank, exhaust, frame, or spare tire. Either the vehicle or the independent suspension must be redesigned.
In addition to providing a smooth ride, the suspension system of a vehicle must perform several distinct functions: attach the wheels and tires to the vehicle; control tire position with respect to the vehicle body; maintain proper wheel alignment and location as the vehicle traverses bumps, potholes, and uneven road surfaces; stabilize the vehicle's attitude during acceleration, braking, and cornering; and transmit forces generated by the tires to direct vehicle motion.
An example of a force generated by the tires is the lateral force generated during turning when the tire pushes against the ground to change the direction of the vehicle. A suspension can be designed to turn the wheel in a certain direction and by a certain magnitude according to that lateral force. This effect is accomplished in a typical four-link suspension by engineering some flex or bend into the wheel carrier or knuckle. Because the wheel carrier is commonly a single metal blade, engineering in the desired amount of flex is complicated, and the part must often be relatively thin.
It would be desirable, therefore, to provide a multi-link independent rear suspension assembly that overcomes the aforementioned and other disadvantages.